Our FBS will fluctuate constantly throughout the day due to the filling/empting of the stomach and food. To find out if you are diabetic you need to have a Glucose tolerance test taken which is a 3hour test. You are underweight for your height. Recommend a Heart Healthy diet which is a moderate fat diet to help you stay healthy and gain weight. You need approximately 1800-2000 calories per day which is spread across 3-5 meals a day with snacks between meals. Moderate fat diet means = use polyunsaturated (omega 3, corn oil, nuts, etc) fats and monounsaturated (olive oil, canola oil, peanut oil, etc) fats, no saturated fats (high fat snack foods, butter, fat spreads) and no trans fats. Eat low fat meats (chicken, fish, loin of pork) or non-meat sources (soy products, nuts), low fat vegetarian combinations (rice & beans, pasta & beans, low fat cheese & pasta), low fat and substitute dairy products (1% milk, low fat/fat free yogurts, low fat soy milk/soy yogurt), use plant oils, non trans-fat margarines, and eat a lot of fruits and vegetables. Eat daily high fiber breads and cereals (oatmeal). Try nutrient dense drinks 1-2 a day, either purchase them, such as Ensure or Boost, or make your own milkshakes - milk, ice cream, and frozen fruit blended together or yogurt smoothies - yogurt, milk, and frozen fruit blended together for additional calories, protein and nutrients to help increase your weight.